1. Technical Field
Embodiments of the invention relate generally to off highway vehicles (OHVs), such as mine trucks. Particular embodiments relate to improving fuel economy of OHVs.
2. Discussion of Art
In the mining industry, large off-highway vehicles (“OHVs”) are used to haul heavy payloads excavated from open pit mines. OHVs usually employ electrically motorized wheels for propelling or retarding the vehicle in an energy efficient manner. In particular, OHVs typically utilize a large horsepower diesel engine in conjunction with an alternator, a main traction inverter, and a pair of wheel drive assemblies housed within the rear tires of the vehicle. The diesel engine is directly associated with the alternator such that the diesel engine drives the alternator. The alternator powers a main traction power converter, in which power semiconductor devices commutate the alternator output current to provide electrical power having a controlled voltage and frequency for electric drive motors of the two wheel drive assemblies.
A typical OHV hauls anywhere from sixty to four hundred tons of material on a chassis and body weighing from about fifty up to about two hundred tons, for gross vehicle weight of as much as six hundred tons. Typical haul distances are from one to five miles depending on the age of mine, with mine road grades sometimes exceeding ten percent. Clearly, diesel fuel is a significant cost in the extraction of mineral resources. Indeed, a typical OHV fuel tank may hold more than two thousand liters of fuel. A recent government survey indicated that a single mining company's haul truck OHVs consumed nearly 30 TJ (760×10^6 liters) of diesel fuel each year.
Thus, it is highly desirable to improve the fuel economy of OHVs.